Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, which already signal safety. The description adds context beyond that: the AUTH_REQUIRED failure condition, the fact that invitees are not tracked (only a private count), and the absence of rewards. These details shape how the agent should frame the tool to the user. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-organized: core purpose first, then critical prerequisite, followed by output usage and caveats. Every sentence carries weight—no filler. Though longer than typical, it's justified given the tool's edge cases and user-facing nuance.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with no parameters and no output schema, the description covers everything an agent needs: the return format, the preconditions, the error path, and the behavioral context (no reward, privacy). It fully equips the agent to call and interpret the result correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 0 parameters, the schema provides no semantic info. The description compensates by explaining the return structure (ref, url, share_text) and the ready-to-forward nature of share_text. This goes beyond the empty schema and adds practical meaning for the agent.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a clear, specific action: 'Create a shareable Pairoa invite link for the current user.' It names the exact resource and what it returns, distinguishing it naturally from sibling tools like claim_account or publish_need, which serve different purposes. The purpose is unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states the precondition ('ONLY works after the user has claimed an account (claim_account)') and the error behavior (AUTH_REQUIRED). It also instructs the agent on how to use the output (relay share_text as-is, offer bare url) and warns against over-promotion since invites carry no reward. This is textbook when-to-use guidance that minimizes misuse.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.